Abstract:

A novel method of stress prerelease is proposed to address the problems in the stress-release process for soft rock tunnels with highground stress. To accomplish stress prerelease,the rock mass is mechanically vibrated, thereby reducing deformation in subsequent tunnel support structures. FLAC3D software is employed to analyze the practical applicability of the mechanical vibration method, revealing the influence of four factors, namely vibration mode, vibration frequency, vibration amplitude, and vibration duration, on the stress release effect. Consequently, conclusions are obtained as follows: (1) The optimal vibration mode of duallateral staggered vibration is selected by comparing the deformation ratio of the tunnels. (2) When the vibration frequency matches the system′s resonant frequency, the stressrelease effect is optimal, and it increases with increasing vibration amplitude, whereas it slightly decreases and stabilizes after surpassing a certain limit. (3) After certain duration of vibration, the high ground stress in the rock mass within the vibration influence range has been substantially released, and the continuous vibration does not further expand the influence range of stress release. (4) The optimal condition of stress release effect is determined, further validating the effectiveness of this approach.

Key words: soft rock tunnel, bench method, mechanical vibration, high ground stress, stress release effect, vibration method, vibration frequency, vibration amplitude, vibration duration